Two distinguishable sounds can be heard during the cycle of the beating heart when listened to with a stethoscope. The heart sounds are usually described as a lup-dup sound. These sounds are due to the closing of the valves of the heart. Unusual heart sounds are called murmurs.

Review Date: 5/1/2008Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.